I haven't bought them from Amazon - they take a cut and hike up the prices. I've gone to the company website.
We should be able to use them up in time - I'm planning on using them for carbonating, serving and purging the kegs too.
If all else fails and we have some left we can ask for a month extension and / or put them in the soda stream.
We don't need to go anywhere - the driver picks them up from your door for you - it's no effort to put them back in a box and hand to the driver. You don't even need to label them up. They've made it really easy.
AND there's no hideously expensive deposit charges on the cylinders, because quite frankly, we can't afford to wait for that refunding. Sodastream can charge what they want because there's very little competition - until now!
Perhaps you should do more research before you practise the art of 'armchair expertise'.
This company setup suits our situation perfectly, so as soon as I saw it I was on it like a car bonnet!